A hydrogen storage alloy is accommodated in a hydrogen storage alloy tank and charges and discharges a hydrogen gas. However, since the hydrogen storage alloy itself expands and contracts by 30% at most with the charging and discharging of the hydrogen gas, stress generated at that time gives strain to the hydrogen storage alloy tank to cause tank deformation and, in an extreme case, there may be generated cracks on the tank. As a method for alleviating the stress generated by the alloy expansion to suppress the tank strain, there is a method of accommodating a hydrogen storage alloy material, which has been made as a resin composite material by mixing a resin and carbon fiber with a hydrogen storage alloy, in a hydrogen storage alloy tank.
A general hydrogen storage alloy powder becomes a dry flowable state but, in the case where a gel-like resin having a viscosity of 500 to 10,000 mPa·s and consistency and carbon fiber are added and mixed thereto in appropriate amounts, since the hydrogen storage alloy contained in the resin composite material becomes a wet sand-like hydrogen storage alloy, it becomes difficult to fill the alloy into a cylinder-type hydrogen storage alloy tank having a small mouth (opening) as a pressure tank.
In a conventional method for filling a hydrogen storage alloy into a tank, it is common to perform the filling manually by a worker. As methods for filling a hydrogen storage alloy efficiently and with good productivity, techniques shown in PTLs 1 and 2 are disclosed.
PTL 1 discloses a method of dispersing a hydrogen storage alloy powder into a fluid, injecting the dispersion into a reaction tank, and removing the fluid component afterward. PTL 2 discloses a method of replacing small rooms partitioned with air curtains by an inert gas and continuously filling an alloy with minimum contamination in the filling rooms while hydrogen storage alloy tanks are transferred on a belt conveyor. Moreover, PTL 2 describes a technique that can fill the alloy into all over the tank regardless of the internal structure by imparting vibration to the hydrogen storage alloy tank.